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<p align=center class=western id=c8tq0 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq1 size=4 style=FONT-SIZE:16pt><b id=c8tq2>Classlib v.
  2.03</b></font>
</p>
<p align=center class=western id=c8tq3 style=MARGIN-BOTTOM:0pt>
  <b id=c8tq4><font id=c8tq5 size=4 style=FONT-SIZE:16pt>A multiple-inheritance
  class library for Lua</font></b>
</p>
<p align=center class=western id=c8tq6 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq7>
</p>
<p align=justify class=western id=c8tq8 style=MARGIN-BOTTOM:0pt>
  This library is based on the general guidelines on OOP found in the
  <b id=c8tq9>PIL</b> (<b id=c8tq10>Programming in Lua</b> by Roberto
  Ierusalimschy) and is also inspired by the class library in
  <b id=c8tq11>http://lua-users.org/wiki/SimpleLuaClasses,</b> which was taken
  as a starting point.
</p>
<p align=justify class=western id=c8tq12 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq13>
</p>
<p align=justify class=western id=c8tq14 style=MARGIN-BOTTOM:0pt>
  It offers a full-featured class system in C++ style, including multiple
  inheritance of stateful classes (not just interfaces), shared (like C++
  virtual) derivation and the correct handling of inheritance and ambiguities.
</p>
<p align=justify class=western id=c8tq15 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq16>
</p>
<p align=justify class=western id=c8tq17 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq18>
</p>
<p align=justify class=western id=c8tq19 style=MARGIN-BOTTOM:0pt>
  <b id=c8tq20>Class creation </b>
</p>
<p align=justify class=western id=c8tq21 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq22>
</p>
<p align=justify class=western id=c8tq23 style=MARGIN-BOTTOM:0pt>
  Classes are created by calling
  <font id=c8tq24 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq25><font color=#0000ff id=c8tq26>class()</font></font></font>
  with the optional list of classes from which the new class derives.
</p>
<p class=western id=c8tq27 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq28>
</p>
<p class=western id=c8tq29 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq30 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq31><font color=#0000ff id=c8tq32>A
  = class(P, Q)</font></font></font>
</p>
<p class=western id=c8tq33 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq34><font face="Courier New, monospace" id=c8tq35><font id=c8tq36 size=2 style=FONT-SIZE:11pt>B
  = class(P, Q)</font></font></font>
</p>
<p class=western id=c8tq37 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq38><font face="Courier New, monospace" id=c8tq39><font id=c8tq40 size=2 style=FONT-SIZE:11pt>C
  = class(A, B)</font></font></font>
</p>
<p class=western id=c8tq41 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq42>
</p>
<p align=justify class=western id=c8tq43 style=MARGIN-BOTTOM:0pt>
  Objects or instances are created by calling the class with arguments to the
  constructor. This is the structure of the generated object:
</p>
<p class=western id=c8tq44 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq45>
</p>
<p class=western id=c8tq46 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq47><font face="Courier New, monospace" id=c8tq48><font id=c8tq49 size=2 style=FONT-SIZE:11pt>Cobj
  = C(...)</font></font></font>
</p>
<p class=western id=c8tq50 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq51>
</p>
<div id=bysn style="PADDING:1em 0pt; TEXT-ALIGN:left">
  <img id=yu8k0 src=Classlib_Manual_images/dhpv5rd2_845fqszcvcq_b.jpg style="WIDTH:640px; HEIGHT:331px">
</div>
<br id=c8tq137>
<p align=justify class=western id=c8tq121 style=MARGIN-BOTTOM:0pt>
  An object of type <font color=#0000ff id=c8tq138>C</font> directly contains
  two base objects of type <font color=#0000ff id=c8tq139>A</font> and
  <font color=#0000ff id=c8tq140>B</font>, and indirectly two each of types
  <font color=#0000ff id=c8tq141>P</font> and
  <font color=#0000ff id=c8tq142>Q</font> which are not directly visible from
  <font color=#0000ff id=c8tq143>C</font>. The
  <font color=#0000ff id=c8tq144>A</font> and
  <font color=#0000ff id=c8tq145>B</font> base objects can be accessed from the
  <font color=#0000ff id=c8tq146>C</font> object as:
</p>
<p align=justify class=western id=c8tq147 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq148>
</p>
<p class=western id=c8tq149 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq150 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq151><font color=#0000ff id=c8tq152>Cobj[A],
  Cobj[B]</font></font></font>
</p>
<p class=western id=c8tq153 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq154>
</p>
<p align=justify class=western id=c8tq155 style=MARGIN-BOTTOM:0pt>
  The <font color=#0000ff id=c8tq156>P</font> and
  <font color=#0000ff id=c8tq157>Q</font> objects are not directly accessible
  from the <font color=#0000ff id=c8tq158>C</font> object since their references
  are ambiguous. They can be accessed by their full paths:
</p>
<p class=western id=c8tq159 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq160>
</p>
<p class=western id=c8tq161 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <span id=c8tq162 lang=es-AR><font id=c8tq163 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq164><font color=#0000ff id=c8tq165>Cobj[A][P],
  Cobj[A][Q], Cobj[B][P], Cobj[B][Q]</font></font></font></span>
</p>
<p class=western id=c8tq166 lang=es-AR style=MARGIN-BOTTOM:0pt>
  <br id=c8tq167>
</p>
<p class=western id=c8tq168 lang=es-AR style=MARGIN-BOTTOM:0pt>
  <br id=c8tq169>
</p>
<p align=justify class=western id=c8tq170 style=MARGIN-BOTTOM:0pt>
  <b id=c8tq171>Shared derivation</b>
</p>
<p align=justify class=western id=c8tq172 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq173>
</p>
<p align=justify class=western id=c8tq174 style=MARGIN-BOTTOM:0pt>
  Shared derivation is roughly equivalent to C++ virtual derivation:
</p>
<p class=western id=c8tq175 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq176>
</p>
<p class=western id=c8tq177 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq178><font face="Courier New, monospace" id=c8tq179><font id=c8tq180 size=2 style=FONT-SIZE:11pt>X
  = class(P, shared(Q))</font></font></font>
</p>
<p class=western id=c8tq181 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq182><font face="Courier New, monospace" id=c8tq183><font id=c8tq184 size=2 style=FONT-SIZE:11pt>Y
  = class(P, shared(Q))</font></font></font>
</p>
<p class=western id=c8tq185 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq186><font face="Courier New, monospace" id=c8tq187><font id=c8tq188 size=2 style=FONT-SIZE:11pt>Z
  = class(X, Y)</font></font></font>
</p>
<p class=western id=c8tq189 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq190>
</p>
<p class=western id=c8tq191 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq192><font face="Courier New, monospace" id=c8tq193><font id=c8tq194 size=2 style=FONT-SIZE:11pt>Zobj
  = Z(...)</font></font></font>
</p>
<p align=justify class=western id=c8tq195 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq274>
  <br id=c8tq275>
  <div id=fn7o style="PADDING:1em 0pt; TEXT-ALIGN:left">
    <img id=xx200 src=Classlib_Manual_images/dhpv5rd2_846v3d4h4g7_b.jpg style="WIDTH:640px; HEIGHT:341px">
  </div>
  The shared derivation of <font color=#0000ff id=c8tq278>X</font> and
  <font color=#0000ff id=c8tq279>Y</font> from
  <font color=#0000ff id=c8tq280>Q</font> results in a single
  <font color=#0000ff id=c8tq281>Q</font> base object. This object is visible
  from the <font color=#0000ff id=c8tq282>Z</font> object, since its reference
  is unambiguous. It can be accessed directly or following any of its full
  paths:
</p>
<p class=western id=c8tq283 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq284>
</p>
<p class=western id=c8tq285 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <span id=c8tq286 lang=es-AR><font id=c8tq287 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq288><font color=#0000ff id=c8tq289>Zobj[Q]
  == Zobj[X][Q] == Zobj[Y][Q]</font></font></font></span>
</p>
<p class=western id=c8tq290 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq291>
</p>
<p class=western id=c8tq292 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq293>
</p>
<p class=western id=c8tq294 style=MARGIN-BOTTOM:0pt>
  <b id=c8tq295>Populating the class</b>
</p>
<p class=western id=c8tq296 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq297>
</p>
<p align=justify class=western id=c8tq298 style=MARGIN-BOTTOM:0pt>
  When a new class is created by the
  <font id=c8tq299 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq300><font color=#0000ff id=c8tq301>class()</font></font></font>
  function, it includes attributes (methods and properties) inherited from the
  base classes according to inheritance rules that will be explained later.
  After that, the class may be populated by adding new attributes or redefining
  inherited ones:
</p>
<p align=justify class=western id=c8tq302 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq303>
</p>
<p align=justify class=western id=c8tq304 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font color=#0000ff id=c8tq305><font face="Courier New, monospace" id=c8tq306><font id=c8tq307 size=2 style=FONT-SIZE:11pt>Account
  = class()</font></font></font>
</p>
<p align=justify class=western id=c8tq308 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq309>
</p>
<p align=justify class=western id=c8tq310 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq311 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq312><font color=#0000ff id=c8tq313>function
  Account:__init(initial)</font></font></font>
</p>
<p align=justify class=western id=c8tq314 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq315 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq316><font color=#0000ff id=c8tq317>
  self.balance = initial or 0</font></font></font>
</p>
<p align=justify class=western id=c8tq318 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq319><font face="Courier New, monospace" id=c8tq320><font id=c8tq321 size=2 style=FONT-SIZE:11pt>end</font></font></font>
</p>
<p align=justify class=western id=c8tq322 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq323>
</p>
<p align=justify class=western id=c8tq324 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq325><font face="Courier New, monospace" id=c8tq326><font id=c8tq327 size=2 style=FONT-SIZE:11pt>function
  Account:deposit(amount)</font></font></font>
</p>
<p align=justify class=western id=c8tq328 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq329><font face="Courier New, monospace" id=c8tq330><font id=c8tq331 size=2 style=FONT-SIZE:11pt>
  self.balance = self.balance + amount</font></font></font>
</p>
<p align=justify class=western id=c8tq332 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq333><font face="Courier New, monospace" id=c8tq334><font id=c8tq335 size=2 style=FONT-SIZE:11pt>end</font></font></font>
</p>
<p align=justify class=western id=c8tq336 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq337>
</p>
<p align=justify class=western id=c8tq338 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq339 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq340><font color=#0000ff id=c8tq341>function
  Account:withdraw(amount)</font></font></font>
</p>
<p align=justify class=western id=c8tq342 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq343 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq344><font color=#0000ff id=c8tq345>
  self.balance = self.balance - amount</font></font></font>
</p>
<p align=justify class=western id=c8tq346 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq347><font face="Courier New, monospace" id=c8tq348><font id=c8tq349 size=2 style=FONT-SIZE:11pt>end</font></font></font>
</p>
<p align=justify class=western id=c8tq350 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq351>
</p>
<p align=justify class=western id=c8tq352 style=MARGIN-BOTTOM:0pt>
  Method
  <font id=c8tq353 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq354><font color=#0000ff id=c8tq355>__init()</font></font></font>
  is the constructor; it is called when an instance is created and passed all
  arguments given to the
  <font id=c8tq356 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq357><font color=#0000ff id=c8tq358>__call()</font></font></font>
  operator of the class. For example,
</p>
<p align=justify class=western id=c8tq359 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq360>
</p>
<p align=justify class=western id=c8tq361 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq362 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq363><font color=#0000ff id=c8tq364>myAccount
  = Account(10.00)</font></font></font>
</p>
<p align=justify class=western id=c8tq365 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq366>
</p>
<p align=justify class=western id=c8tq367 style=MARGIN-BOTTOM:0pt>
  creates an account with an initial
  <font id=c8tq368 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq369><font color=#0000ff id=c8tq370>balance
  </font></font></font>of $10.00.
</p>
<p align=justify class=western id=c8tq371 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq372>
</p>
<p align=justify class=western id=c8tq373 style=MARGIN-BOTTOM:0pt>
  If
  <font id=c8tq374 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq375><font color=#0000ff id=c8tq376>__init()
  </font></font></font>is defined, it may call the constructors of the base
  objects explicitly in order to initialize them:
</p>
<p align=justify class=western id=c8tq377 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq378>
</p>
<p align=justify class=western id=c8tq379 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq380 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq381><font color=#0000ff id=c8tq382>NamedAccount
  = class(Account)</font></font></font>
</p>
<p align=justify class=western id=c8tq383 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq384>
</p>
<p align=justify class=western id=c8tq385 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq386><font face="Courier New, monospace" id=c8tq387><font id=c8tq388 size=2 style=FONT-SIZE:11pt>function
  NamedAccount:__init(name, initial)</font></font></font>
</p>
<p align=justify class=western id=c8tq389 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq390><font face="Courier New, monospace" id=c8tq391><font id=c8tq392 size=2 style=FONT-SIZE:11pt>
  self[Account]:__init(initial)</font></font></font>
</p>
<p align=justify class=western id=c8tq393 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq394><font face="Courier New, monospace" id=c8tq395><font id=c8tq396 size=2 style=FONT-SIZE:11pt>
  self.name = name or 'anonymous'</font></font></font>
</p>
<p align=justify class=western id=c8tq397 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq398><font face="Courier New, monospace" id=c8tq399><font id=c8tq400 size=2 style=FONT-SIZE:11pt>end</font></font></font>
</p>
<p align=justify class=western id=c8tq401 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq402>
</p>
<p align=justify class=western id=c8tq403 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq404><font face="Courier New, monospace" id=c8tq405><font id=c8tq406 size=2 style=FONT-SIZE:11pt>myNamedAccount
  = NamedAccount('John', 10.00)</font></font></font>
</p>
<p align=justify class=western id=c8tq407 style="MARGIN-LEFT:0.25in; MARGIN-BOTTOM:0pt">
  <br id=c8tq408>
</p>
<p align=justify class=western id=c8tq409 style=MARGIN-BOTTOM:0pt>
  The library modifies the user-supplied
  <font id=c8tq410 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq411><font color=#0000ff id=c8tq412>__init()
  </font></font></font>by wrapping it in such a way that:
</p>
<p align=justify class=western id=c8tq413 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq414>
</p>
<p align=justify class=western id=c8tq415 style=MARGIN-BOTTOM:0pt>
  1. It will run exactly once per object. This is specially necessary in the
  case of multiple shared inheritance, when a shared base object may be accessed
  following more than one path, in order to protect the object against multiple
  initialization. In our example of shared inheritance given before, the
  <font face="Courier New, monospace" id=c8tq416><font color=#0000ff id=c8tq417>Q</font></font>
  object might otherwise be initialized up to three times.
</p>
<p align=justify class=western id=c8tq418 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq419>
</p>
<p align=justify class=western id=c8tq420 style=MARGIN-BOTTOM:0pt>
  2. Base objects not explicitly initialized by the user-supplied constructor
  are initialized by default with the same arguments received by the constructor
  of the derived object. If this is not adequate, base objects should be
  initialized explicitly.
</p>
<p align=justify class=western id=c8tq421 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq422>
</p>
<p align=justify class=western id=c8tq423 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq424>
</p>
<p align=justify class=western id=c8tq425 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <b id=c8tq426>Named classes and dot scoping</b>
</p>
<p align=justify class=western id=c8tq427 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq428>
</p>
<p align=justify class=western id=c8tq429 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  Accessing the base objects by indexing the object with the base class is
  simple and intuitive. This is the mechanism used by <i id=c8tq430>unnamed</i>
  classes.
</p>
<p align=justify class=western id=c8tq431 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq432>
</p>
<p align=justify class=western id=c8tq433 style=MARGIN-BOTTOM:0pt>
  The library also supports <i id=c8tq434>named</i> classes. Using named
  classes, a base object is accessed by indexing the derived object not with the
  base class, but with the <i id=c8tq435>name</i> of the base class (a string).
  This makes the base object appear as a field of the derived object, the field
  name being the name of the base class. Here is our previous example revisited,
  where
  <font id=c8tq436 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq437><font color=#0000ff id=c8tq438>Account</font></font></font>
  is now a named class whose name is precisely
  <font id=c8tq439 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq440><font color=#0000ff id=c8tq441>'Account'</font></font></font>:
</p>
<p align=justify class=western id=c8tq442 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq443>
</p>
<p align=justify class=western id=c8tq444 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq445><font face="Courier New, monospace" id=c8tq446><font id=c8tq447 size=2 style=FONT-SIZE:11pt>function
  NamedAccount:__init(name, initial)</font></font></font>
</p>
<p align=justify class=western id=c8tq448 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq449 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq450><font color=#0000ff id=c8tq451>
  self.Account:__init(initial)</font></font></font>
</p>
<p align=justify class=western id=c8tq452 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq453><font face="Courier New, monospace" id=c8tq454><font id=c8tq455 size=2 style=FONT-SIZE:11pt>
  self.name = name or 'anonymous'</font></font></font>
</p>
<p align=justify class=western id=c8tq456 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq457><font face="Courier New, monospace" id=c8tq458><font id=c8tq459 size=2 style=FONT-SIZE:11pt>end</font></font></font>
</p>
<p align=justify class=western id=c8tq460 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq461>
</p>
<p align=justify class=western id=c8tq462 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq463><font face="Courier New, monospace" id=c8tq464><font id=c8tq465 size=2 style=FONT-SIZE:11pt>myNamedAccount
  = NamedAccount('John', 10.00)</font></font></font>
</p>
<p align=justify class=western id=c8tq466 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq467>
</p>
<p align=justify class=western id=c8tq468 style=MARGIN-BOTTOM:0pt>
  Note that
  <font id=c8tq469 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq470><font color=#0000ff id=c8tq471>self[Account]
  </font></font></font>has been replaced by
  <font id=c8tq472 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq473><font color=#0000ff id=c8tq474>self.Account</font></font></font>.
  This scoping syntax is more in line with the conventions used by other OO
  languages
</p>
<p align=justify class=western id=c8tq475 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq476>
</p>
<p align=justify class=western id=c8tq477 style=MARGIN-BOTTOM:0pt>
  There are several ways of giving a name to a class. The first one is to simply
  assign its
  <font id=c8tq478 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq479><font color=#0000ff id=c8tq480>__name
  </font></font></font>attribute:
</p>
<p align=justify class=western id=c8tq481 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq482>
</p>
<p align=justify class=western id=c8tq483 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq484 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq485><font color=#0000ff id=c8tq486>Account
  = class()</font></font></font>
</p>
<p align=justify class=western id=c8tq487 style=MARGIN-BOTTOM:0pt>
  <font color=#0000ff id=c8tq488><font face="Courier New, monospace" id=c8tq489><font id=c8tq490 size=2 style=FONT-SIZE:11pt>
  Account.__name = 'Account'</font></font></font>
</p>
<p align=justify class=western id=c8tq491 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq492>
</p>
<p align=justify class=western id=c8tq493 style=MARGIN-BOTTOM:0pt>
  Another way is to pass the class name as a first string argument to
  <font id=c8tq494 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq495><font color=#0000ff id=c8tq496>class()</font></font></font>:
</p>
<p align=justify class=western id=c8tq497 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq498>
</p>
<p align=justify class=western id=c8tq499 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq500 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq501><font color=#0000ff id=c8tq502>Account
  = class('Account')</font></font></font>
</p>
<p align=justify class=western id=c8tq503 style=MARGIN-BOTTOM:0pt>
  <font color=#0000ff id=c8tq504><font face="Courier New, monospace" id=c8tq505><font id=c8tq506 size=2 style=FONT-SIZE:11pt>
  NamedAccount = class('NamedAccount', Account)</font></font></font>
</p>
<p align=justify class=western id=c8tq507 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq508>
</p>
<p align=justify class=western id=c8tq509 style=MARGIN-BOTTOM:0pt>
  Here the classes were named after the variables holding them. If these
  variables are global, there is a shorter way of doing the same thing:
</p>
<p align=justify class=western id=c8tq510 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq511>
</p>
<p align=justify class=western id=c8tq512 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq513 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq514><font color=#0000ff id=c8tq515>class.Account()
  -- same as Account = class('Account', ...)</font></font></font>
</p>
<p align=justify class=western id=c8tq516 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq517 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq518><font color=#0000ff id=c8tq519>
  class.NamedAccount(Account)</font></font></font>
</p>
<p align=justify class=western id=c8tq520 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq521>
</p>
<p align=justify class=western id=c8tq522 style=MARGIN-BOTTOM:0pt>
  This technique is limited to global variables. For classes living in locals
  and upvalues, use explicit naming. In the rest of this document we shall
  assume that classes are named.
</p>
<p align=justify class=western id=c8tq523 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq524>
</p>
<p align=justify class=western id=c8tq525 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq526>
</p>
<p align=justify class=western id=c8tq527 style=MARGIN-BOTTOM:0pt>
  <b id=c8tq528>Object and class attributes</b>
</p>
<p align=justify class=western id=c8tq529 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq530>
</p>
<p align=justify class=western id=c8tq531 style=MARGIN-BOTTOM:0pt>
  Object attributes live in their respective objects. The constructor of the
  <font id=c8tq532 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq533><font color=#0000ff id=c8tq534>Account</font></font></font>
  class, for example, creates a property called
  <font id=c8tq535 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq536><font color=#0000ff id=c8tq537>balance</font></font></font>
  in the
  <font id=c8tq538 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq539><font color=#0000ff id=c8tq540>Account</font></font></font>
  object. The constructor of
  <font id=c8tq541 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq542><font color=#0000ff id=c8tq543>NamedAccount
  </font></font></font>creates a property called
  <font id=c8tq544 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq545><font color=#0000ff id=c8tq546>name</font></font></font>
  in the
  <font id=c8tq547 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq548><font color=#0000ff id=c8tq549>NamedAccount
  </font></font></font>object. Object properties created by methods of a certain
  class never migrate to a derived object; a
  <font id=c8tq550 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq551><font color=#0000ff id=c8tq552>NamedAccount
  </font></font></font>object does not have a
  <font id=c8tq553 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq554><font color=#0000ff id=c8tq555>balance</font></font></font>
  in itself, but in its base
  <font id=c8tq556 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq557><font color=#0000ff id=c8tq558>Account</font></font></font>
  object. In the example above:
</p>
<p align=justify class=western id=c8tq559 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq560>
</p>
<p align=justify class=western id=c8tq561 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq562 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq563><font color=#0000ff id=c8tq564>myNamedAccount.name
  == 'John'</font></font></font>
</p>
<p align=justify class=western id=c8tq565 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq566 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq567><font color=#0000ff id=c8tq568>myNamedAccount.balance
  == nil </font></font></font>
</p>
<p align=justify class=western id=c8tq569 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq570 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq571><font color=#0000ff id=c8tq572>myNamedAccount.Account.balance
  == 10.00</font></font></font>
</p>
<p align=justify class=western id=c8tq573 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq574>
</p>
<p align=justify class=western id=c8tq575 style=MARGIN-BOTTOM:0pt>
  This scheme avoids name clashes between attributes generated by different
  classes, keeps classes independent of each other and allows one to derive from
  classes whose name spaces overlap. It departs from the C++ scheme in the sense
  that base object attributes are not inherited by the derived objects (in C++
  properties of base objects are inherited by the derived object if they are not
  ambiguous) but there is no other reasonable way given the dynamic nature of
  variables in Lua: object properties are not defined statically, they come into
  existence and disappear during program execution.
</p>
<p align=justify class=western id=c8tq576 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq577>
</p>
<p align=justify class=western id=c8tq578 style=MARGIN-BOTTOM:0pt>
  Following the guidelines of Lua OOP (and also departing from C++), this
  library makes class attributes default values for object attributes. This
  feature comes from the fact that classes are metatables of their objects, and
  helps get rid of constructors whose sole purpose is assigning initial default
  values. For example, if an
  <font id=c8tq579 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq580><font color=#0000ff id=c8tq581>Account</font></font></font>
  were to be created always with an initial zero balance, instead of defining a
  constructor one could simply declare:
</p>
<p align=justify class=western id=c8tq582 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq583>
</p>
<p align=justify class=western id=c8tq584 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq585 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq586><font color=#0000ff id=c8tq587>Account.balance
  = 0</font></font></font>
</p>
<p align=justify class=western id=c8tq588 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq589>
</p>
<p align=justify class=western id=c8tq590 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq591 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq592><font color=#0000ff id=c8tq593>myAccount
  = Account() </font></font></font>
</p>
<p align=justify class=western id=c8tq594 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq595>
</p>
<p align=justify class=western id=c8tq596 style=MARGIN-BOTTOM:0pt>
  Before the balance is assigned to for the first time,
  <font id=c8tq597 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq598><font color=#0000ff id=c8tq599>myAccount.balance</font></font></font>
  refers to the class property and reads zero. On the first deposit, however,
  the
  <font id=c8tq600 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq601><font color=#0000ff id=c8tq602>Account:deposit()</font></font></font>
  method creates a
  <font id=c8tq603 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq604><font color=#0000ff id=c8tq605>balance</font></font></font>
  property in the
  <font id=c8tq606 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq607><font color=#0000ff id=c8tq608>Account</font></font></font>
  object (it does not modify the class property) and thereafter
  <font id=c8tq609 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq610><font color=#0000ff id=c8tq611>myAccount.balance</font></font></font>
  refers to the object property. If sometime later the user assigns
  <font id=c8tq612 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq613><font color=#0000ff id=c8tq614>myAccount.balance
  = nil,</font></font></font> the object property disappears and
  <font id=c8tq615 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq616><font color=#0000ff id=c8tq617>myAccount.balance</font></font></font>
  refers to the class property again. This behavior must be taken into account
  if class properties are used as default values: assigning
  <font id=c8tq618 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq619><font color=#0000ff id=c8tq620>nil</font></font></font>
  to an object property defaulted by a class property seems to actually assign
  it the default value.
</p>
<p align=justify class=western id=c8tq621 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq622>
</p>
<p align=justify class=western id=c8tq623 style=MARGIN-BOTTOM:0pt>
  Class properties can also be used as class global variables (as in C++) and
  assigned to, but in that case they must be accessed directly and not through
  the objects. For example, by making the direct assignment
</p>
<p align=justify class=western id=c8tq624 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq625>
</p>
<p align=justify class=western id=c8tq626 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq627 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq628><font color=#0000ff id=c8tq629>Account.balance
  = 4.50 </font></font></font>
</p>
<p align=justify class=western id=c8tq630 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq631>
</p>
<p align=justify class=western id=c8tq632 style=MARGIN-BOTTOM:0pt>
  all accounts created thereafter will have an initial balance of $4.50.
</p>
<p align=justify class=western id=c8tq633 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq634>
</p>
<p align=justify class=western id=c8tq635 style=MARGIN-BOTTOM:0pt>
  Class functions (i.e. those functions that are not methods) should also be
  called directly, never through the objects. This is another departure from
  C++, which accepts both ways of calling a static or class method as
  equivalent. See the following section for an explanation why this is not so
  with this library.
</p>
<p align=justify class=western id=c8tq636 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq637>
</p>
<p align=justify class=western id=c8tq638 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq639>
</p>
<p align=justify class=western id=c8tq640 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <b id=c8tq641>Inheritance</b>
</p>
<p align=justify class=western id=c8tq642 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq643>
</p>
<p align=justify class=western id=c8tq644 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  Taking the
  <font id=c8tq645 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq646><font color=#0000ff id=c8tq647>NamedAccount</font></font></font>
  example, we can make a deposit by calling
</p>
<p align=justify class=western id=c8tq648 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq649>
</p>
<p align=justify class=western id=c8tq650 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq651 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq652><font color=#0000ff id=c8tq653>myNamedAccount.Account:deposit(2.00)
  </font></font></font>
</p>
<p align=justify class=western id=c8tq654 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq655>
</p>
<p align=justify class=western id=c8tq656 style=MARGIN-BOTTOM:0pt>
  But the
  <font id=c8tq657 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq658><font color=#0000ff id=c8tq659>deposit()</font></font></font>
  method is <i id=c8tq660>inherited</i> by
  <font id=c8tq661 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq662><font color=#0000ff id=c8tq663>NamedAccount
  </font></font></font>from
  <font id=c8tq664 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq665><font color=#0000ff id=c8tq666>Account</font></font></font>,
  so we can simply say
</p>
<p align=justify class=western id=c8tq667 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq668>
</p>
<p align=justify class=western id=c8tq669 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq670 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq671><font color=#0000ff id=c8tq672>myNamedAccount:deposit(2.00)
  </font></font></font>
</p>
<p align=justify class=western id=c8tq673 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq674>
</p>
<p align=justify class=western id=c8tq675 style=MARGIN-BOTTOM:0pt>
  and we get exactly the same result.
</p>
<p align=justify class=western id=c8tq676 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq677>
</p>
<p align=justify class=western id=c8tq678 style=MARGIN-BOTTOM:0pt>
  Inheritance rules are simple: the first rule says that an attribute is
  inherited from a base class if there is no ambiguity. Attributes that have the
  same name in different bases are not inherited. Multiple inheritances of the
  same attribute from the same base are ambiguous unless they originate in a
  shared base, the reason being that unshared base objects of the same class
  have their own separate states and methods accessing their states must be
  called with a full path to make sure that they receive the correct
  <font id=c8tq679 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq680><font color=#0000ff id=c8tq681>self</font></font></font>.
</p>
<p align=justify class=western id=c8tq682 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq683>
</p>
<p align=justify class=western id=c8tq684 style=MARGIN-BOTTOM:0pt>
  For example:
</p>
<p align=justify class=western id=c8tq685 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq686>
</p>
<p align=justify class=western id=c8tq687 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq688 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq689><font color=#0000ff id=c8tq690>class.SavingsAccount(Account)</font></font></font>
</p>
<p align=justify class=western id=c8tq691 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq692 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq693><font color=#0000ff id=c8tq694>class.CurrentAccount(Account)</font></font></font>
</p>
<p align=justify class=western id=c8tq695 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq696 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq697><font color=#0000ff id=c8tq698>class.CombinedAccount(SavingsAccount,
  CurrentAccount)</font></font></font>
</p>
<p align=justify class=western id=c8tq699 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq700>
</p>
<p align=justify class=western id=c8tq701 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq702><font face="Courier New, monospace" id=c8tq703><font id=c8tq704 size=2 style=FONT-SIZE:11pt>myCombinedAccount
  = CombinedAccount()</font></font></font>
</p>
<p align=justify class=western id=c8tq705 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq706 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq707><font color=#0000ff id=c8tq708>myCombinedAccount:deposit(2.00)
  ← Error, deposit is nil</font></font></font>
</p>
<p align=justify class=western id=c8tq709 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq710>
</p>
<p align=justify class=western id=c8tq711 style=MARGIN-BOTTOM:0pt>
  The
  <font id=c8tq712 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq713><font color=#0000ff id=c8tq714>deposit()</font></font></font>method
  of the
  <font id=c8tq715 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq716><font color=#0000ff id=c8tq717>Account</font></font></font>
  class is inherited by both
  <font id=c8tq718 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq719><font color=#0000ff id=c8tq720>SavingsAccount
  </font></font></font>and
  <font id=c8tq721 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq722><font color=#0000ff id=c8tq723>CurrentAccount</font></font></font>,
  but not by
  <font id=c8tq724 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq725><font color=#0000ff id=c8tq726>CombinedAccount
  </font></font></font>since it would be ambiguous as the
  <font id=c8tq727 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq728><font color=#0000ff id=c8tq729>Account</font></font></font>
  base is not shared. These are correct:
</p>
<p align=justify class=western id=c8tq730 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq731>
</p>
<p align=justify class=western id=c8tq732 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq733 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq734><font color=#0000ff id=c8tq735>myCombinedAccount.CurrentAccount.Account:deposit(2.00)</font></font></font>
</p>
<p align=justify class=western id=c8tq736 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq737 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq738><font color=#0000ff id=c8tq739>myCombinedAccount.CurrentAccount:deposit(2.00)</font></font></font>
</p>
<p align=justify class=western id=c8tq740 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq741>
</p>
<p align=justify class=western id=c8tq742 style=MARGIN-BOTTOM:0pt>
  Both will increment
  <font id=c8tq743 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq744><font color=#0000ff id=c8tq745>myCombinedAccount.CurrentAccount.Account.balance
  </font></font></font>by $2.00.
</p>
<p align=justify class=western id=c8tq746 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq747>
</p>
<p align=justify class=western id=c8tq748 style=MARGIN-BOTTOM:0pt>
  There would exist a
  <font id=c8tq749 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq750><font color=#0000ff id=c8tq751>CombinedAccount:deposit()
  </font></font></font>method if
  <font id=c8tq752 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq753><font color=#0000ff id=c8tq754>SavingsAccount
  </font></font></font>and
  <font id=c8tq755 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq756><font color=#0000ff id=c8tq757>CurrentAccount
  </font></font></font>were derived from
  <font id=c8tq758 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq759><font color=#0000ff id=c8tq760>shared(Account)</font></font></font>.
  That would create a single
  <font id=c8tq761 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq762><font color=#0000ff id=c8tq763>Account</font></font></font>
  base object and a single
  <font id=c8tq764 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq765><font color=#0000ff id=c8tq766>balance
  </font></font></font>and would avoid the ambiguity, although it would
  certainly not make any sense in this particular application.
</p>
<p align=justify class=western id=c8tq767 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq768>
</p>
<p align=justify class=western id=c8tq769 style=MARGIN-BOTTOM:0pt>
  The second inheritance rule says that when methods are inherited, they are not
  merely copied from the base class to the derived class, but modified (wrapped)
  so that they call the original methods with
  <font id=c8tq770 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq771><font color=#0000ff id=c8tq772>self</font></font></font>
  values corresponding to the base objects of their class.
</p>
<p align=justify class=western id=c8tq773 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq774>
</p>
<p align=justify class=western id=c8tq775 style=MARGIN-BOTTOM:0pt>
  Recall that these two operations were reported to produce identical results:
</p>
<p align=justify class=western id=c8tq776 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq777>
</p>
<p align=justify class=western id=c8tq778 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq779 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq780><font color=#0000ff id=c8tq781>myNamedAccount.Account:deposit(2.00)
  (1) </font></font></font>
</p>
<p align=justify class=western id=c8tq782 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq783 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq784><font color=#0000ff id=c8tq785>myNamedAccount:deposit(2.00)
  (2)</font></font></font>
</p>
<p align=justify class=western id=c8tq786 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq787>
</p>
<p align=justify class=western id=c8tq788 style=MARGIN-BOTTOM:0pt>
  The original
  <font id=c8tq789 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq790><font color=#0000ff id=c8tq791>deposit()</font></font></font>belongs
  to the
  <font id=c8tq792 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq793><font color=#0000ff id=c8tq794>Account</font></font></font>
  class. In
  <font id=c8tq795 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq796><font color=#0000ff id=c8tq797>(1)</font></font></font>
  the original method is called with
  <font id=c8tq798 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq799><font color=#0000ff id=c8tq800>myNamedAccount.Account</font></font></font>
  (the
  <font id=c8tq801 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq802><font color=#0000ff id=c8tq803>Account</font></font></font>
  object) as
  <font id=c8tq804 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq805><font color=#0000ff id=c8tq806>self</font></font></font>.
  In
  <font id=c8tq807 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq808><font color=#0000ff id=c8tq809>(2)</font></font></font>
  the inherited version is called with
  <font id=c8tq810 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq811><font color=#0000ff id=c8tq812>myNamedAccount
  </font></font></font>(the
  <font id=c8tq813 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq814><font color=#0000ff id=c8tq815>NamedAccount
  </font></font></font>object) as
  <font id=c8tq816 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq817><font color=#0000ff id=c8tq818>self</font></font></font>.
  This inherited version in turn calls the original one passing it
  <font id=c8tq819 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq820><font color=#0000ff id=c8tq821>self.Account
  </font></font></font>as
  <font id=c8tq822 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq823><font color=#0000ff id=c8tq824>self</font></font></font>.
  The runtime cost of this wrapping mechanism is indexing on
  <font id=c8tq825 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq826><font color=#0000ff id=c8tq827>self</font></font></font>
  and calling a function, no matter how many levels of derivation are involved.
</p>
<p align=justify class=western id=c8tq828 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq829>
</p>
<p align=justify class=western id=c8tq830 style=MARGIN-BOTTOM:0pt>
  When a class is created, the derivation process wraps all inherited functions
  assuming that they are methods, since there is no way to tell. The user is
  expected to avoid calling functions that are not methods as if they were;
  class functions should be called only directly, never through the objects. The
  only cost of wrapping class functions, then, is to generate some (small)
  useless code.
</p>
<p align=justify class=western id=c8tq831 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq832>
</p>
<p align=justify class=western id=c8tq833 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq834>
</p>
<p align=justify class=western id=c8tq835 style=MARGIN-BOTTOM:0pt>
  <b id=c8tq836>Metamethods and indexing</b>
</p>
<p align=justify class=western id=c8tq837 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq838>
</p>
<p align=justify class=western id=c8tq839 style=MARGIN-BOTTOM:0pt>
  Classes may freely define metamethods like
  <font id=c8tq840 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq841><font color=#0000ff id=c8tq842>__call()</font></font></font>,
  <font id=c8tq843 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq844><font color=#0000ff id=c8tq845>__add()</font></font></font>,
  <font id=c8tq846 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq847><font color=#0000ff id=c8tq848>__mul()</font></font></font>,
  etc. They behave like any other method and are inherited if they are not
  ambiguous.
</p>
<p align=justify class=western id=c8tq849 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq850>
</p>
<p align=justify class=western id=c8tq851 style=MARGIN-BOTTOM:0pt>
  Indexing, however, is special. The methametods controlling indexing
  (<font id=c8tq852 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq853><font color=#0000ff id=c8tq854>__index()</font></font></font>
  and
  <font id=c8tq855 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq856><font color=#0000ff id=c8tq857>__newindex()</font></font></font>)
  cannot be defined by the user directly, since that would dismantle the whole
  class machinery.
</p>
<p align=justify class=western id=c8tq858 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq859>
</p>
<p align=justify class=western id=c8tq860 style=MARGIN-BOTTOM:0pt>
  The class library supports indexing control by letting users define two
  special methods:
  <font id=c8tq861 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq862><font color=#0000ff id=c8tq863>__get()
  </font></font></font>and
  <font id=c8tq864 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq865><font color=#0000ff id=c8tq866>__set()</font></font></font>.
  These methods are not meant to be called directly (they are internally
  renamed) but if they are defined they are called when indexing operations
  (square bracket or dot-field accesses) are performed on an instance of a
  class.
</p>
<p align=justify class=western id=c8tq867 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq868>
</p>
<p align=justify class=western id=c8tq869 style=MARGIN-BOTTOM:0pt>
  Classes are metatables of their instances. Normally, a class
  <font id=c8tq870 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq871><font color=#0000ff id=c8tq872>C</font></font></font>
  has:
</p>
<p align=justify class=western id=c8tq873 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq874>
</p>
<p align=justify class=western id=c8tq875 style=MARGIN-BOTTOM:0pt>
  <font color=#0000ff id=c8tq876><font face="Courier New, monospace" id=c8tq877><font id=c8tq878 size=2 style=FONT-SIZE:11pt>
  __index == C</font></font></font>
</p>
<p align=justify class=western id=c8tq879 style=MARGIN-BOTTOM:0pt>
  <font color=#0000ff id=c8tq880><font face="Courier New, monospace" id=c8tq881><font id=c8tq882 size=2 style=FONT-SIZE:11pt>
  __newindex == nil</font></font></font>
</p>
<p align=justify class=western id=c8tq883 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq884>
</p>
<p align=justify class=western id=c8tq885 style=MARGIN-BOTTOM:0pt>
  When
  <font id=c8tq886 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq887><font color=#0000ff id=c8tq888>__get()</font></font></font>
  is defined, an
  <font id=c8tq889 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq890><font color=#0000ff id=c8tq891>__index()
  </font></font></font>handler is installed. This handler is called every time
  an attempt is made to read a missing object attribute. The handler first looks
  for the attribute in the class. If it finds it there, it just returns it. If
  the attribute is not found in the class, the handler calls
  <font id=c8tq892 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq893><font color=#0000ff id=c8tq894>__get()
  </font></font></font>with the name of the attribute, and returns whatever
  <font id=c8tq895 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq896><font color=#0000ff id=c8tq897>__get(name)
  </font></font></font>returns.
</p>
<p align=justify class=western id=c8tq898 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq899>
</p>
<p align=justify class=western id=c8tq900 style=MARGIN-BOTTOM:0pt>
  When
  <font id=c8tq901 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq902><font color=#0000ff id=c8tq903>__set()</font></font></font>
  is defined, a
  <font id=c8tq904 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq905><font color=#0000ff id=c8tq906>__newindex()
  </font></font></font>handler is installed. This handler is called every time
  an attempt is made to assign a value to a missing object attribute. The
  handler starts by calling
  <font id=c8tq907 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq908><font color=#0000ff id=c8tq909>__set()
  </font></font></font>with the name and value of the attribute. If
  <font id=c8tq910 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq911><font color=#0000ff id=c8tq912>__set(name,
  value) </font></font></font>returns
  <font id=c8tq913 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq914><font color=#0000ff id=c8tq915>true</font></font></font>,
  this indicates that
  <font id=c8tq916 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq917><font color=#0000ff id=c8tq918>__set()</font></font></font>
  has handled the assignment and there is nothing else to do. Otherwise, the
  assignment was not handled and the handler creates the attribute directly in
  the main body of the object.
</p>
<p align=justify class=western id=c8tq919 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq920>
</p>
<p align=justify class=western id=c8tq921 style=MARGIN-BOTTOM:0pt>
  This mechanism is useful for defining classes that behave like arrays or
  tables and keep the elements separate from the main body of the object. Since
  the elements are not found directly in the object,
  <font id=c8tq922 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq923><font color=#0000ff id=c8tq924>__get()
  </font></font></font>and
  <font id=c8tq925 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq926><font color=#0000ff id=c8tq927>__set()</font></font></font>
  are called on every access. One can also think of applications where objects
  are proxies and the elements are stored remotely and accessed through a
  communications interface.
</p>
<p align=justify class=western id=c8tq928 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq929>
</p>
<p align=justify class=western id=c8tq930 style=MARGIN-BOTTOM:0pt>
  As an example, consider this excerpt from a
  <font id=c8tq931 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq932><font color=#0000ff id=c8tq933>Tuple</font></font></font>
  class that behaves like a contiguous array indexed by integers from
  <font id=c8tq934 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq935><font color=#0000ff id=c8tq936>1
  </font></font></font>to the current size plus one. It has two fields: a table
  <font id=c8tq937 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq938><font color=#0000ff id=c8tq939>elem</font></font></font>
  for holding the elements and the current size
  <font id=c8tq940 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq941><font color=#0000ff id=c8tq942>n</font></font></font>.
  Element
  <font id=c8tq943 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq944><font color=#0000ff id=c8tq945>[n+1]</font></font></font>
  is a sentinel, reading it returns
  <font id=c8tq946 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq947><font color=#0000ff id=c8tq948>nil
  </font></font></font>and assigning it increases the size by one.
</p>
<p align=justify class=western id=c8tq949 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq950>
</p>
<p align=justify class=western id=c8tq951 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq952><font face="Courier New, monospace" id=c8tq953><font id=c8tq954 size=2 style=FONT-SIZE:11pt>function
  Tuple:__get(i)</font></font></font>
</p>
<p align=justify class=western id=c8tq955 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq956><font face="Courier New, monospace" id=c8tq957><font id=c8tq958 size=2 style=FONT-SIZE:11pt>
  if type(i) ~= 'number' then return nil end</font></font></font>
</p>
<p align=justify class=western id=c8tq959 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq960 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq961><font color=#0000ff id=c8tq962>
  assert(i &gt;= 1 and i &lt;= self.n + 1, 'Invalid index')</font></font></font>
</p>
<p align=justify class=western id=c8tq963 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq964><font face="Courier New, monospace" id=c8tq965><font id=c8tq966 size=2 style=FONT-SIZE:11pt>
  return self.elem[i]</font></font></font>
</p>
<p align=justify class=western id=c8tq967 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq968><font face="Courier New, monospace" id=c8tq969><font id=c8tq970 size=2 style=FONT-SIZE:11pt>end</font></font></font>
</p>
<p align=justify class=western id=c8tq971 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <br id=c8tq972>
</p>
<p align=justify class=western id=c8tq973 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq974><font face="Courier New, monospace" id=c8tq975><font id=c8tq976 size=2 style=FONT-SIZE:11pt>function
  Tuple:__set(i, v)</font></font></font>
</p>
<p align=justify class=western id=c8tq977 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq978><font face="Courier New, monospace" id=c8tq979><font id=c8tq980 size=2 style=FONT-SIZE:11pt>
  if type(i) ~= 'number' then return false end</font></font></font>
</p>
<p align=justify class=western id=c8tq981 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq982 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq983><font color=#0000ff id=c8tq984>
  assert(i &gt;= 1 and i &lt;= self.n + 1, 'Invalid index')</font></font></font>
</p>
<p align=justify class=western id=c8tq985 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq986 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq987><font color=#0000ff id=c8tq988>
  if v == nil then --remove</font></font></font>
</p>
<p align=justify class=western id=c8tq989 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq990><font face="Courier New, monospace" id=c8tq991><font id=c8tq992 size=2 style=FONT-SIZE:11pt>
  if i &lt;= self.n then</font></font></font>
</p>
<p align=justify class=western id=c8tq993 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq994><font face="Courier New, monospace" id=c8tq995><font id=c8tq996 size=2 style=FONT-SIZE:11pt>
  table.remove(self.elem, i)</font></font></font>
</p>
<p align=justify class=western id=c8tq997 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq998><font face="Courier New, monospace" id=c8tq999><font id=c8tq1000 size=2 style=FONT-SIZE:11pt>
  self.n = self.n - 1</font></font></font>
</p>
<p align=justify class=western id=c8tq1001 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq1002><font face="Courier New, monospace" id=c8tq1003><font id=c8tq1004 size=2 style=FONT-SIZE:11pt>
  end</font></font></font>
</p>
<p align=justify class=western id=c8tq1005 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq1006><font face="Courier New, monospace" id=c8tq1007><font id=c8tq1008 size=2 style=FONT-SIZE:11pt>
  return true</font></font></font>
</p>
<p align=justify class=western id=c8tq1009 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq1010><font face="Courier New, monospace" id=c8tq1011><font id=c8tq1012 size=2 style=FONT-SIZE:11pt>
  end </font></font></font>
</p>
<p align=justify class=western id=c8tq1013 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1014 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1015><font color=#0000ff id=c8tq1016>
  if i == self.n + 1 then self.n = i end --append</font></font></font>
</p>
<p align=justify class=western id=c8tq1017 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq1018><font face="Courier New, monospace" id=c8tq1019><font id=c8tq1020 size=2 style=FONT-SIZE:11pt>
  self.elem[i] = v</font></font></font>
</p>
<p align=justify class=western id=c8tq1021 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq1022><font face="Courier New, monospace" id=c8tq1023><font id=c8tq1024 size=2 style=FONT-SIZE:11pt>
  return true</font></font></font>
</p>
<p align=justify class=western id=c8tq1025 style="MARGIN-LEFT:0.5in; MARGIN-BOTTOM:0pt">
  <font color=#0000ff id=c8tq1026><font face="Courier New, monospace" id=c8tq1027><font id=c8tq1028 size=2 style=FONT-SIZE:11pt>end</font></font></font>
</p>
<p align=justify class=western id=c8tq1029 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1030>
</p>
<p align=justify class=western id=c8tq1031 style=MARGIN-BOTTOM:0pt>
  Note how
  <font id=c8tq1032 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1033><font color=#0000ff id=c8tq1034>__get()
  </font></font></font>and
  <font id=c8tq1035 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1036><font color=#0000ff id=c8tq1037>__set()</font></font></font>
  carefully reject non-numeric indexes by returning
  <font id=c8tq1038 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1039><font color=#0000ff id=c8tq1040>nil</font></font></font>
  and
  <font id=c8tq1041 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1042><font color=#0000ff id=c8tq1043>false
  </font></font></font>respectively. These methods must be written with great
  care so that they do not re-enter indefinitely. Use
  <font id=c8tq1044 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1045><font color=#0000ff id=c8tq1046>rawget()</font></font></font>
  and
  <font id=c8tq1047 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1048><font color=#0000ff id=c8tq1049>rawset()</font></font></font>
  when necessary.
</p>
<p align=justify class=western id=c8tq1050 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  This class can be used as follows:
</p>
<p align=justify class=western id=c8tq1051 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq1052>
</p>
<p align=justify class=western id=c8tq1053 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1054 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1055><font color=#0000ff id=c8tq1056>
  t = Tuple(11, 22, 33)</font></font></font>
</p>
<p align=justify class=western id=c8tq1057 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1058 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1059><font color=#0000ff id=c8tq1060>
  = t --&gt; (11, 22, 33)</font></font></font>
</p>
<p align=justify class=western id=c8tq1061 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1062 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1063><font color=#0000ff id=c8tq1064>
  = t[2] --&gt; 22</font></font></font>
</p>
<p align=justify class=western id=c8tq1065 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font color=#0000ff id=c8tq1066><font face="Courier New, monospace" id=c8tq1067><font id=c8tq1068 size=2 style=FONT-SIZE:11pt>
  t[2] = nil</font></font></font>
</p>
<p align=justify class=western id=c8tq1069 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1070 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1071><font color=#0000ff id=c8tq1072>
  = t --&gt; (11, 33)</font></font></font>
</p>
<p align=justify class=western id=c8tq1073 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1074 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1075><font color=#0000ff id=c8tq1076>
  t[3] = 333</font></font></font>
</p>
<p align=justify class=western id=c8tq1077 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1078 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1079><font color=#0000ff id=c8tq1080>
  = t --&gt; (11, 33, 333)</font></font></font>
</p>
<p align=justify class=western id=c8tq1081 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1082 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1083><font color=#0000ff id=c8tq1084>
  t[5] = 55 --&gt; Error, invalid index</font></font></font>
</p>
<p align=justify class=western id=c8tq1085 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1086>
</p>
<p align=justify class=western id=c8tq1087 style=MARGIN-BOTTOM:0pt>
  The indexing hooks have a cost in terms of performance, but it is only paid by
  classes that define the
  <font id=c8tq1088 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1089><font color=#0000ff id=c8tq1090>__get()
  </font></font></font>and
  <font id=c8tq1091 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1092><font color=#0000ff id=c8tq1093>__set()</font></font></font>
  methods. Other classes are not affected. If a class derives from an indexing
  base but does not need the indexing operations, it may just define
  <font id=c8tq1094 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1095><font color=#0000ff id=c8tq1096>__get
  = nil</font></font></font>
  and<font id=c8tq1097 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1098><font color=#0000ff id=c8tq1099>
  __set = nil</font></font></font>; this will remove the indexing hooks.
</p>
<p align=justify class=western id=c8tq1100 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1101>
</p>
<p align=justify class=western id=c8tq1102 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1103>
</p>
<p align=justify class=western id=c8tq1104 style=MARGIN-BOTTOM:0pt>
  <b id=c8tq1105>Implementation</b>
</p>
<p align=justify class=western id=c8tq1106 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1107>
</p>
<p align=justify class=western id=c8tq1108 style=MARGIN-BOTTOM:0pt>
  The library is implemented in a single file,
  <font id=c8tq1109 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1110><font color=#0000ff id=c8tq1111>classlib.lua</font>.
  </font></font>Public interface:
</p>
<p align=justify class=western id=c8tq1112 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1113>
</p>
<p align=justify class=western id=c8tq1114 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1115 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1116><font color=#0000ff id=c8tq1117>class([name,][bases])
  </font></font></font>Creates a new class that derives from zero or more
  classes. If
  <font id=c8tq1118 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1119><font color=#0000ff id=c8tq1120>name</font></font></font>
  exists it creates a named class, otherwise an unnamed class;
  <font id=c8tq1121 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1122><font color=#0000ff id=c8tq1123>bases</font></font></font>
  is a list of classes or values returned by
  <font id=c8tq1124 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1125><font color=#0000ff id=c8tq1126>shared()</font></font></font>.
</p>
<p align=justify class=western id=c8tq1127 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1128>
</p>
<p align=justify class=western id=c8tq1129 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1130 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1131><font color=#0000ff id=c8tq1132>class.name([bases])
  </font></font></font>Creates a new named class and assigns it to a global
  variable with the same name:
  <font id=c8tq1133 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1134><font color=#0000ff id=c8tq1135>class.name(bases)
  </font></font></font>is the same as
  <font id=c8tq1136 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1137><font color=#0000ff id=c8tq1138>name
  = class('name', bases) </font></font></font>where
  <font id=c8tq1139 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1140><font color=#0000ff id=c8tq1141>name</font></font></font>
  is global.
</p>
<p align=justify class=western id=c8tq1142 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1143>
</p>
<p align=justify class=western id=c8tq1144 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1145 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1146><font color=#0000ff id=c8tq1147>shared(class)</font></font></font>
  Wraps a class so that it can be passed as an argument to
  <font id=c8tq1148 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1149><font color=#0000ff id=c8tq1150>class()</font></font></font>
  for shared derivation.
</p>
<p align=justify class=western id=c8tq1151 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1152>
</p>
<p align=justify class=western id=c8tq1153 style=MARGIN-BOTTOM:0pt>
  There is a version of the library that only supports unnamed classes and
  square-bracket scoping,
  <font id=c8tq1154 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1155><font color=#0000ff id=c8tq1156>unclasslib.lua</font></font></font>.
  If named classes are not used this version should be a bit more efficient,
  since it eliminates one level of indexing when accessing the base objects.
  Classes are created by
  <font id=c8tq1157 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1158><font color=#0000ff id=c8tq1159>class([bases])</font></font></font>.
  No name argument is allowed, and assigning the
  <font id=c8tq1160 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1161><font color=#0000ff id=c8tq1162>__name</font></font></font>
  attribute of a class has no effect.
</p>
<p align=justify class=western id=c8tq1163 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1164>
</p>
<p align=justify class=western id=c8tq1165 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  There is also a group of utility functions for checking types and interface
  support:
</p>
<p align=justify class=western id=c8tq1166 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq1167>
</p>
<p align=justify class=western id=c8tq1168 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1169 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1170><font color=#0000ff id=c8tq1171>typeof(v)
  </font></font></font>Returns
  <font id=c8tq1172 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1173><font color=#0000ff id=c8tq1174>'object'</font></font></font>
  if
  <font id=c8tq1175 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1176><font color=#0000ff id=c8tq1177>v</font></font></font>
  is an object,
  <font id=c8tq1178 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1179><font color=#0000ff id=c8tq1180>'class'</font></font></font>
  if it is a class,
  <font id=c8tq1181 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1182><font color=#0000ff id=c8tq1183>type(v)</font></font></font>
  otherwise.
</p>
<p align=justify class=western id=c8tq1184 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq1185>
</p>
<p align=justify class=western id=c8tq1186 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1187 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1188><font color=#0000ff id=c8tq1189>classof(v)
  </font></font></font>Returns the class
  of<font id=c8tq1190 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1191><font color=#0000ff id=c8tq1192>
  v</font></font></font> if
  <font id=c8tq1193 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1194><font color=#0000ff id=c8tq1195>v
  </font></font></font>is an object or a class,
  <font id=c8tq1196 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1197><font color=#0000ff id=c8tq1198>nil
  </font></font></font>otherwise.
</p>
<p align=justify class=western id=c8tq1199 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1200>
</p>
<p align=justify class=western id=c8tq1201 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1202 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1203><font color=#0000ff id=c8tq1204>classname(v)
  </font></font></font>Returns the name of the class
  of<font id=c8tq1205 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1206><font color=#0000ff id=c8tq1207>
  v</font></font></font> if
  <font id=c8tq1208 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1209><font color=#0000ff id=c8tq1210>v
  </font></font></font>is an object or a class and the class is named,
  <font id=c8tq1211 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1212><font color=#0000ff id=c8tq1213>nil
  </font></font></font>otherwise.
</p>
<p align=justify class=western id=c8tq1214 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1215>
</p>
<p align=justify class=western id=c8tq1216 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1217 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1218><font color=#0000ff id=c8tq1219>implements(v,
  class) </font></font></font>True if
  <font id=c8tq1220 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1221><font color=#0000ff id=c8tq1222>v
  </font></font></font>is an object or a class that implements the interface of
  <font id=c8tq1223 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1224><font color=#0000ff id=c8tq1225>class</font></font></font>.
</p>
<p align=justify class=western id=c8tq1226 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1227>
</p>
<p align=justify class=western id=c8tq1228 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1229 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1230><font color=#0000ff id=c8tq1231>is_a(v,
  class) </font></font></font>True if
  <font id=c8tq1232 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1233><font color=#0000ff id=c8tq1234>v
  </font></font></font>is an object or a class of class
  <font id=c8tq1235 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1236><font color=#0000ff id=c8tq1237>class</font></font></font>
  or derives from
  <font id=c8tq1238 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1239><font color=#0000ff id=c8tq1240>class</font></font></font>
  and implements its interface.
</p>
<p align=justify class=western id=c8tq1241 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1242>
</p>
<p align=justify class=western id=c8tq1243 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  When a class is created, it has a few initial methods:
</p>
<p align=justify class=western id=c8tq1244 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq1245>
</p>
<p align=justify class=western id=c8tq1246 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1247 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1248><font color=#0000ff id=c8tq1249>__call(...)</font></font></font>
  Calling the class creates an instance. Arguments are passed to the
  constructor.
</p>
<p align=justify class=western id=c8tq1250 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1251>
</p>
<p align=justify class=western id=c8tq1252 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <font id=c8tq1253 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1254><font color=#0000ff id=c8tq1255>__init(...)</font></font></font>
  Default constructor.
</p>
<p align=justify class=western id=c8tq1256 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1257>
</p>
<p align=justify class=western id=c8tq1258 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1259 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1260><font color=#0000ff id=c8tq1261>implements(class)</font></font></font>
  Method to determine if an object or class implements the interface of a target
  class.
</p>
<p align=justify class=western id=c8tq1262 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq1263>
</p>
<p align=justify class=western id=c8tq1264 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1265 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1266><font color=#0000ff id=c8tq1267>is_a(class)</font></font></font>
  Method to determine if an object or class is of the type of a target class.
</p>
<p align=justify class=western id=c8tq1268 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1269>
</p>
<p align=justify class=western id=c8tq1270 style=MARGIN-BOTTOM:0pt>
  The
  <font id=c8tq1271 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1272><font color=#0000ff id=c8tq1273>is_a()
  </font></font></font>and
  <font id=c8tq1274 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1275><font color=#0000ff id=c8tq1276>implements()
  </font></font></font>methods are somehow special since they can be applied to
  both classes and objects.
</p>
<p align=justify class=western id=c8tq1277 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1278>
</p>
<p align=justify class=western id=c8tq1279 style=MARGIN-BOTTOM:0pt>
  The
  <font id=c8tq1280 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1281><font color=#0000ff id=c8tq1282>implements()
  </font></font></font>method checks that an object or class supports the
  interface of the target class. The interface of a class is the set of its
  callable attributes (functions and objects with a
  <font id=c8tq1283 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1284><font color=#0000ff id=c8tq1285>__call()</font></font></font>
  operator). The method merely checks that these attributes <i id=c8tq1286>exist
  and are callable</i>; certainly this does not guarantee that they are
  semantically correct.
</p>
<p align=justify class=western id=c8tq1287 style="MARGIN-LEFT:2.13in; TEXT-INDENT:-2.13in; MARGIN-BOTTOM:0pt">
  <br id=c8tq1288>
</p>
<p align=justify class=western id=c8tq1289 style=MARGIN-BOTTOM:0pt>
  The
  <font id=c8tq1290 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1291><font color=#0000ff id=c8tq1292>is_a()
  </font></font></font>method checks whether the object or class is of the same
  class as the target class or derives from the target <i id=c8tq1293>and</i>
  implements it. For example,
</p>
<p align=justify class=western id=c8tq1294 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1295>
</p>
<p align=justify class=western id=c8tq1296 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq1297 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1298><font color=#0000ff id=c8tq1299>myNamedAccount:is_a(Account)
  == true</font></font></font>
</p>
<p align=justify class=western id=c8tq1300 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq1301 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1302><font color=#0000ff id=c8tq1303>
  myCombinedAccount:is_a(Account) == false</font></font></font>
</p>
<p align=justify class=western id=c8tq1304 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1305>
</p>
<p align=justify class=western id=c8tq1306 style="MARGIN-BOTTOM:0pt; page-break-inside:avoid; page-break-after:avoid">
  The last one fails because although
  <font id=c8tq1307 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1308><font color=#0000ff id=c8tq1309>CombinedAccount</font></font></font>
  derives from
  <font id=c8tq1310 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1311><font color=#0000ff id=c8tq1312>Account</font></font></font>,
  it does not support its
  <font id=c8tq1313 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1314><font color=#0000ff id=c8tq1315>deposit()</font></font></font>
  and
  <font id=c8tq1316 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1317><font color=#0000ff id=c8tq1318>withdraw()</font></font></font>
  methods since they are ambiguous. This means that a
  <font id=c8tq1319 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1320><font color=#0000ff id=c8tq1321>CombinedAccount</font></font></font>
  cannot be passed to a function expecting an
  <font id=c8tq1322 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1323><font color=#0000ff id=c8tq1324>Account</font></font></font>,
  since that function could blindly attempt to call those methods.
</p>
<p align=justify class=western id=c8tq1325 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1326>
</p>
<p align=justify class=western id=c8tq1327 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1328>
</p>
<p align=justify class=western id=c8tq1329 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <b id=c8tq1330>Reserved names</b>
</p>
<p align=justify class=western id=c8tq1331 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq1332>
</p>
<p align=justify class=western id=c8tq1333 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  The implementation of the class library reserves some attribute names for
  internal use:
</p>
<p align=justify class=western id=c8tq1334 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <br id=c8tq1335>
</p>
<p align=justify class=western id=c8tq1336 style="MARGIN-BOTTOM:0pt; page-break-after:avoid">
  <font id=c8tq1337 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1338><font color=#0000ff id=c8tq1339>
  __index __newindex __type</font></font></font>
</p>
<p align=justify class=western id=c8tq1340 style=MARGIN-BOTTOM:0pt>
  <font id=c8tq1341 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1342><font color=#0000ff id=c8tq1343>
  __class __bases __shared __inherited __from __user_init __initialized
  __user_get __user_set</font></font></font>
</p>
<p align=justify class=western id=c8tq1344 style=MARGIN-BOTTOM:0pt>
  <br id=c8tq1345>
</p>
<p align=justify class=western id=c8tq1346 style=MARGIN-BOTTOM:0pt>
  Please leave these alone or just avoid using names starting with two
  underscores, with the exception of
  <font id=c8tq1347 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1348><font color=#0000ff id=c8tq1349>__name</font></font></font>,<font id=c8tq1350 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1351><font color=#0000ff id=c8tq1352>
  __init()</font></font></font>,<font id=c8tq1353 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1354><font color=#0000ff id=c8tq1355>
  __get()</font></font></font>,<font id=c8tq1356 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1357><font color=#0000ff id=c8tq1358>
  __set()</font></font></font> and the metamethods like
  <font id=c8tq1359 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1360><font color=#0000ff id=c8tq1361>__call()</font></font></font>,<font id=c8tq1362 size=2 style=FONT-SIZE:11pt><font face="Courier New, monospace" id=c8tq1363><font color=#0000ff id=c8tq1364>
  __add()</font></font></font>, etc. which may be safely defined.
</p></body>
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